We've recently been debugging a few issues with our current SPARQL implementation so the next version will have a SPARQL engine that returns correct results more of the time (hopefully all the time but we can't guarantee that there aren't issues we haven't found yet). As detailed on the Known Issues page there is a bug in the 0.1.1 Alpha release whereby some queries result in the engine unnecessarily duplicating results, this can be worked around by using SELECT DISTINCT but the cause of the issue has been traced and corrected in development builds as of about a week ago.

I've also been looking at whether to include any of the proposed SPARQL 1.1 features that are in the Working Draft document from the W3C SPARQL Working Group. I have decided to go ahead and include aggregates in dotNetRDFs implementation since they were the thing I most often wanted to be able to do in testing stuff. Latest development builds committed to SVN this afternoon add support for AVG, COUNT, COUNT(*), MAX, MIN and SUM aggregates, currently the MAX and MIN aggregates only operate over the numeric data space. Until the working group sees fit to clarify how they expect such aggregates to behave over mixed data and how they decide what type of maximum or minimum to compute I'm not going to expand the capability any further. As part of this implementation all aggregates support aliasing to a variable name using AS ?alias syntax, if not specified explicitly an aggregate gets mapped to the variable ?Result in the Result Set. The aggregate result is a typed Literal Node (Integer for COUNT aggregates) and the widest numeric type for all others. A final limitation to this experimental implementation of aggregates is that only 1 aggregate is supported in a SELECT clause and currently we don't support any kind of GROUP BY/HAVING clauses in relation to aggregates.

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Two additional Known Issues with Version 0.1.1 Alpha have been identified:

1. Query
   • Some SPARQL Queries will result in unnecessarily duplicated results
2. URI Resolution
   • QNames of the form :name used when there is no default namespace defined are resolved against the Base URI incorrectly

Both these issues have fixes which we are currently implementing, we will include these fixes in the next release of the Library i.e. these issues are not serious enough to warrant an interim bug fix re-release.

Tags: 0.1.1, Bugs, Errors, Issues, Known Issues

We have today published a re-release of Version 0.1.1 Alpha in order to address a couple of bugs that were found in this version which we decided were important to fix promptly. The official build number is now 0.1.1.20316

If you downloaded the library from around 12:30 today (British Summer Time) then you will have downloaded the re-release. The re-release builds will be up on SourceForge shortly

See the Known Issues page to see the issues that have been addressed in this re-release

Tags: 0.1.1, Alpha, Bug Fix, Download, Downloads, Fix, Release, Releases

A couple of new Known Issues with Version 0.1.1 Alpha have been identified. These will be fixed shortly and we will likely just release an updated build of this version with the changes applied.

The issues are:

1. It is possible to create a Graph that when parsed loses some of it's Triples because the Blank Node IDs assigned by the user inadvertently clash with auto-assigned IDs
2. When using some of the improved writer classes with the compression level set to None invalid syntax is produced

Tags: 0.1.1, Bugs, Issues, Known Issues